The reason I wanted to use Media Library Assistant for the Flickity carousel was to coordinate with a set of albums that can be easily navigated by the site visitor, and easily managed by the site owner. This process is split into two posts. Here’s today’s outline:

1. Use MLA to apply Att. Categories to images, where the categories are the albums.
2. Use WordPress’s get_terms() function to generate a list of all categories, and within each, a list of all subcategories. Make each list a link that applies a query string to the URL when it is clicked.
3. Use the value in the query string to build the appropriate mla_gallery shortcode, and have a default for when the page is first loaded. Execute the shortcode with do_shortcode().